You can add or remove replica nodes on the Nodes tab to improve the disaster recovery capabilities of your instance. You can also enable the read/write splitting feature. After this feature is enabled, your instance automatically detects read and write requests and forwards them accordingly without requiring you to modify your application code. This feature is ideal for high-concurrency scenarios where read operations occur more frequently than write operations.
Prerequisites
The instance is deployed in cloud-native mode.
The instance is a Redis Community Edition or Tair (Enterprise Edition) memory-optimized or persistent memory-optimized instance.
The instance has a capacity of 1 GB or higher.
The instance is a high availability (HA) instance.
Notes
For dual-zone instances, we recommend that you configure at least two nodes in both the primary zone and the secondary zone:
Primary zone: one primary node and one replica/read-only node. When HA is triggered, the system preferentially performs a failover within the same zone to avoid increased access latency caused by a failover to the secondary zone.
Secondary zone: two replica/read-only nodes.
Add or remove replica nodes
The standard architecture supports 1 to 9 replica nodes. The cluster architecture supports 1 to 4 replica nodes for each shard.
Log on to the console and go to the Instances page. In the top navigation bar, select the region in which the instance that you want to manage resides. Then, find the instance and click the instance ID.
In the navigation pane on the left, click Nodes.
On the Nodes page, click Operation column and select Modify.
In the panel that appears, add or remove replica nodes.
Follow the instructions to complete the payment process.
After the payment is completed, the instance status changes to Changing Configuration. Wait for 1 to 5 minutes until the instance status changes to Running, which indicates that the configuration change is complete. You can view the progress on the instance details page.
Enable read/write splitting
The read/write splitting feature uses a star replication architecture. All read-only nodes synchronize data from the primary node, resulting in low data synchronization latency.
Enabling or disabling Read/Write Splitting causes a transient connection to your instance and triggers data migration in the background. Adjusting the number of read-only nodes does not cause a transient connection. Perform this operation during off-peak hours. Ensure that the instance does not receive many write requests during the operation and that your application can automatically reconnect to the instance.
Log on to the console and go to the Instances page. In the top navigation bar, select the region in which the instance that you want to manage resides. Then, find the instance and click the instance ID.
In the navigation pane on the left, click Nodes.
Turn on the Read/Write Splitting switch.
In the panel that appears, confirm the instance configuration information and order cost.Click Pay.
NoteThe specifications of new read replicas are the same as the specifications of the instance.
Follow the instructions to complete the payment process.
After the payment is completed, the instance status changes to Changing Configuration. Wait for 1 to 5 minutes until the instance status changes to Running, which indicates that the configuration change is complete. You can view the progress on the instance details page.
NoteIf the instance is deployed across two zones, the instance provides connection addresses for both the primary and secondary zones (both addresses support read and write operations). You need to actively distinguish between the connection addresses of the primary and secondary zones and direct requests for the secondary zone to the connection address of the secondary zone to achieve proximity access and load balancing.
(Optional) More management operations.
Adjust the number of read-only nodes: On the Nodes page, click Operation column and select Modify. The standard architecture supports 1 to 9 read-only nodes, and the cluster architecture supports 1 to 4 read-only nodes for each shard.
Disable the read/write splitting feature: Turn off the Read/Write Splitting switch.
FAQ
Q: Why do I receive the error message "The primary availability zone requires at least one read-only node" when I try to enable read/write splitting?
A: This error occurs because your instance is deployed across multiple zones with a standard architecture (one primary node in the primary zone and one replica node in the secondary zone). The minimum requirement for read/write splitting is that the primary zone must have one primary node and one read-only node.
You need to first add one replica node to the primary zone to ensure that the primary zone has two nodes, and then enable read/write splitting.